U.S. Pat. No. 4,625,107 to Planke describes a method for contour recognition of transparent objects by use of illumination.
U.S. Pat. No. 4,859,862 to Planke et al. describes a device for generating, detecting, and characterizing a raster image of the contour of an object.
U.S. Pat. No. 4,996,440 to Nordbryhn describes a device for measuring regions of an object to determine dimensions of such object, by directing a light beam towards an object, receiving light beams reflected from object, and calculating travel time of beam to and from the object.
U.S. Pat. No. 5,898,169 to Nordbryhn describes a device for generating, detecting, and recognizing a contour image of a liquid container, and a processing means for comparing such with predetermined container feature data to recognize contour image of container.